Unraveling the Power of Disorder: A Bioinspired Cuttlebone Structure With Superior Strength, Energy Absorption and Isotropy.

Lightweight architected materials with superior mechanical performance and tailored isotropy are of critical importance for advanced engineering applications such as aerospace and protective structures. Inspired by the discrete disordered structure of cuttlebone, this study proposes a "controlled disorder" design strategy. Leveraging micro-CT to extract structural features, discrete topological equations are employed to tailor the unit cells, which are then fabricated into biomimetic specimens via 3D printing. Experiments and simulations reveal that as the level of disorder increases, the compressive strength and specific energy absorption significantly rise by approximately 41% and 206%, respectively, while the modulus remains remarkably constant. Concurrently, shear anisotropy is markedly reduced, with the ratios of minimum to maximum shear stiffness and shear strength increasing by 1981 % and 45 %, respectively, the latter exceeding 0.9-signalling a dramatic transition toward isotropy. Increasing the number of unit cells further promotes isotropy. Notably, the fully disordered specimens outperform existing high-performance benchmarks in both normalized specific strength and specific energy absorption. Overall, this work uncovers the strengthening and isotropizing mechanisms in biomimetic discrete disordered structures, providing a novel perspective and a robust design paradigm for the development of next-generation high-performance mechanical metamaterials.